This setting in your web.config file is able to be updated to control this.

  <httpruntime maxrequestlength="1000000" executiontimeout="9999999">
  </httpruntime>

Remember to save your changes for the settings to be applied...

It seems that IIS7 now has a different parameter for this setting, and it's in bytes rather than KB. "In IIS7, you specify the maximum size of a file to be uploaded to the website by using the maxAllowedContentLength setting (system.webServer/security/requestFiltering/requestLimits >> maxAllowedContentLength)." For example, you can try something like this in your web.config:

<system.webServer> 
<security> 
<requestFiltering> 
<requestLimits maxAllowedContentLength="1000000000" ></requestLimits>